In the common optical scanning system upon which this invention improves, a light beam is deflected by a facet of a rotating mirror and the light from the mirror is directed by an optical system of lenses and reflectors to a photoconductive surface. The light beam is modulated, typically by off and on modulation, to apply an image to the photoconductive surface. The optical system must direct and focus the light.
Since the mirror is rotated at constant speed and the modulation interval is constant, a distortion is experienced known as f-theta distortion. This results in points on a plane surface being scanned having varied spacing over the scanned length.
This invention provides a highly stable, accurate, and cost effective optical system which also corrects f-theta distortion. The following United States patents are illustrative of this technology, but are not to a monolithic optical scanner: U.S. Pat. Nos. 5,009,472 to Morimoto; 4,917,483 to Nakao and 4,847,492 to Houk.